Another ESS AMT-1a pyramid rebuild thread

Discussion in 'Speakers' started by 13stoploss, Nov 23, 2015.

  1. 13stoploss

    13stoploss Active Member

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    This is my first real thread here, aside from my (heated) introduction to AK. Hopefully this is the right thread for this rebuild, instead of the DIY?

    I grew up with ESS in the house. My old man bought a pair of AMT Monitors in 1991 from a guy whose wife made him get rid of them. So, when I got back from my second tour to Iraq (stop lossed) in 2006, Uncle Sam apologized by giving me a nice lump sum paycheck in late 2009. In early 2010, living in Southern California, I bought a pair of AMT Monitors from a guy in Tahoe on eBay for $399 (before the recession, they were selling for $1200-1600 on eBay, and about $800-1000 during this timeframe). He said they worked great (uh huh, rotting foam, "You mean, they're not supposed to be like that?")! and me and my old man drove all the way up there to get 'em, and turned right back around and brought 'em home.

    Four new sets of foam surrounds and two new diaphragm replacements later, they were rocking.



    OK, that's a pretty laughable video. But they worked!

    Fast forward a few years, a cross-continental move, a little bit more capital and better taste, I decided to bi-amp the AMT Monitors with a new old-stock ESS active electronic crossover, a Marantz 2230 receiver powering the low freq's, and a Dynaco ST-70 tube amp powering the high freq's.



    My lousy iPhone audio does it no justice, but boy was that a sweet setup.

    Anyway, the point of this thread. I sold the Marantz and the Dynaco because I wanted more oomph. I bought a new Emotiva XSP-1 gen2 pre-amp, and I've been saving for a new amp. But then I found these AMT-1a pyramid cabinets for sale on eBay and I noticed the guy lived six miles away. So, I messaged him and offered $80 if his auction didn't sell. He accepted, we met up, and I had a new project! Which means I blew my amp fund on some used foam disc passives and AMT-1a crossovers.

    The plan was to ratfock the drivers and AMT Heil from my Monitors for use on the AMT-1a, then sell the rebuilt AMT 1a speakers for brand new ESS driver and passive components, then also buy new AMT Heils. Along the way, things got complicated.

    Teaser. Here's when I got everything working, sitting in front of my Klipsch Forte (I), and then I tore it all a part again. Wait, what? Tore a part after THIS?

    [​IMG]
     
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  2. 13stoploss

    13stoploss Active Member

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    Step 1: new crossover.

    With the intention of selling these speakers, I bought affordable Dayton caps and resistors and new speaker-cable terminals from Parts Express. I planned to re-use the original tiny-gauge hook-up wire. Unfortunately, or maybe fortunately, the new modern, bulbous caps didn't fit.

    This is basically the first peak into the rabbit hole. What follows, in this reply and in those to come, is full on falling into Wonderland.

    Here's the first layout. Clearly, this wasn't going to work.

    [​IMG]

    Then I measured the inside cabinet, the part where the crossover board attaches upside down inside the cabinet, so that the mid-range and brilliance L-Pots face upward, externally, on top of the speaker and behind the Heil AMT.

    Then I bought some plywood.

    Inside the cabinet, there was a little bit of extra width, but not much at all in height. I measured the L-Pot knob spacing, cut a board, then spray painted the top with flat black paint. On the reverse side, I laid out the new crossover components to see how they fit. It looked very nice.

    [​IMG]

    However, this was a bad board, and it, too, wasn't going to work: there wasn't enough lead in the caps to reach the terminal strip, and there wasn't enough room between the L-Pots for the newer, larger, modern cap. So I made a new board. And for various other mistakes, I made two more boards until I had it right. And then I made another matching board.

    [​IMG]

    Next, I worked on the new speaker-cable terminals. I wanted something more versatile, something that would accept banana plugs. So, I wired in these terminals from PE. It was a very tight fit, and it would be weeks before I learned that, once I plugged cable into them, yes, it worked, but the cable was bent and squished into a stressful 90* angle.

    [​IMG]

    After that, I decided to work on the cabinets. These had a serial number etched into the walnut veneer, so I sanded them down. Then I taped 'em off, spray painted the top, the base, and the motor board with a flat black paint. Two coats. They looked very nice. Then I wiped on some Howard Feed-N-Wax to bring back the shine on the veneer.

    [​IMG]

    When that was done, I bolted everything up. Left channel good, right channel dead.

    SHlT.

    Did I mention that this was my first real speaker project? That I've never before used my hands for anything other than throwing a baseball, marching through Iraq with an M4/M203 rifle and grenade launcher, and loving the woman of my dreams?

    My first thought was that I must've screwed up the crossover. I pulled the board and decided that some of my soldering could use some cleaning up. Few days pass, I complete that, hook everything up and--left channel high freq good, right channel low freq good.

    FOCK.

    I pulled both the boards. I knew for fact that the left channel worked fine. I left it alone. I looked again at the right channel board. Started playing around with one of the caps, and then one of the leads broke off. SHlT. So, I bought another cap. A week later, I plug it in, solder it up, AND?

    Left channel good, right channel high freq good.

    OH, GAHDAMN.

    I switch the boards, move right to left and left to right. SAME PROBLEM.

    Did I mention that I'm also in grad school? That, on top of a normal government job, I'm also going to school at night? And that my kids, with Little League and ballet, occupy my weekends?

    I'm frustrated. Progress is slow. I just want to fix these, sell them, buy new components, and move on.

    For two more weeks, the speakers sit. Then, a chance encounter.

    I'm selling some Altec Lansing 887a Capri Mini Monitors that I rebuilt on Craigslist (by the way, I've met Craig Newmark. Had lunch with him. Very nice guy. Passionate about customer service, but very socially awkward and self deprecating). I don't consider this a real rebuild because all I did was buy new Piezo ring tweeters and replace one cap and one resistor on the crossover. They sounded good. They were neat. Perfect for a hipster and budding audiophile vinyl setup. Anyway, so, this prospective buyer comes over to demo the small Altec's. Very serious. Brings some CDs he's very familiar with. Ultimately, he decides these aren't for him, but he notices my AMT-1 cabinets sitting in the corner of my living room. We start talking about ESS and how much we each love them, and he asks about the project, and to let him know when I'm done. Asks me what's left. I tell him I just need to finish the crossovers. Now, he's really piqued, and I'm excited that I may have a buyer! And this is what transformed me and my thinking about rebuilds. This is when I became interested and obsessed with not just great sound, but also presentation. He asked if I was using new hook-up wire. And I wasn't. I was re-using the miniscule seemingly-38-awg original wire. Dude leaves, and I'm back to the drawing board.
     
    Last edited: Nov 23, 2015
  3. 13stoploss

    13stoploss Active Member

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    I am also reserving this reply space #2
     
  4. 13stoploss

    13stoploss Active Member

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    I forgot to mention that, with the AMT Monitors cannibalized for this project, and this project not yet functioning, I blow into the fund for a Craigslist steal that I couldn't pass up: I found a pair of Klipsch Forte I in great shape for $300.

    I love them. They're great. But you know what? They have something the ESS don't have, but they just aren't that exciting, either. Great for brass and jazz, but it just seems to be missing something. Anyway, I now have speakers to listen with while rebuilding, and something to compare once I'm done.

    Of course, this nearly neuters the new amp and new ESS components fund. By now then, I've already discovered Bob Crites and the upgrades I can make for these Klipsch. And, coupled with what the prospective Altec listener says + seeing the Crites crossovers, and others, I see that the crossover world can actually be very good looking, and clean, and orderly. Seriously, ESS, what's with the cheap particle board and gobs of glue?

    So, you see, I'm now fully divested in #projectpyramid. Now I've got to redesign the redesigned crossover board. With what's left of my funds, I decide to replace one more cap, buy new screw-down barrier strips from Allied Electronics, and for some added zing, some new 20-awg, pvc-insulated, nylon-braided hook-up wire. I de-solder everything. I trash the original 48-awg wire (ok, it's not 48, but maybe 22/24 awg?), De-Oxit the L-Pots, scrape the glue-gun detritus from my custom-cut boards, and begin anew.

    Here's the result:

    [​IMG]

    I'm proud of this. To me, it looks clean, and neat, and orderly. Everything that ESS wasn't in its heyday. Upgraded. New. It's going to sound so BADASS, right?!

    Before hooking everything up, I've got some extra work to do. First? I bored out the cubby housing the speaker cable terminals:

    [​IMG]

    [​IMG]

    [​IMG]

    Then, after looking at more crossover and speaker builds, I learn about shrink-wrapping! CAN ONE CONTAIN THIS EXCITEMENT? Hell yeah! I bought some shrink wrap tubes from my local hardware store, busted out the old heat gun from my Army boot-polishing days, and got to work SHRINK-WRAPPING ALL THE THINGS!

    [​IMG]

    [​IMG]
     
    Last edited: Nov 23, 2015
  5. 13stoploss

    13stoploss Active Member

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    Saving this for the next edit
     
  6. gizzyman47

    gizzyman47 Super Member

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    I got a set of these also. The guy I bought them from spray painted them black! Need to strip and sand to get them back to their former glory. Enjoy seeing your rebuild of these great speakers
     
  7. 13stoploss

    13stoploss Active Member

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    So, literally, everything was done except for the final cabinet preparations. I'd put on some Howard's, maybe do another spray paint coat up top, then sell these bad boys, right?

    RIGHT?

    When I plugged in the new crossovers, I was good on left, and good on right low freq.

    )(*&^%$#@$%^&*(&^$%#%$ <this is an accurate brain-scan simulation of what was going on in my head. Plus many other four-letter words.

    I laid down. I just played music and listened to the 3/4 stereo sound. Defeated. And gahdamit (I know I've mentioned it, but I used to be in the Army. I went to Iraq twice. I like to focking swear. So, I misspell my bloody, dirty mouth so that you can adequately understand how I felt going through this ordeal. Want to read my words censored? The New York Times censored me here.), it sounded so good. And it broke me.

    Two months. 30+ hours labor. Few hundred dollars on caps and wires and barrier strips and wood and spray paint and polish...

    And then, something funny. Something I haven't mentioned before. As I was unplugging these ESS AMT-1a speakers and plugging in my Klipsch Forte, I noticed, when I pressed play, that my Klipsch had the same imaging problem. What do I mean by that?

    Here is my Parts Express 50w*2 amp.

    Here is another pic.

    Here is the sound, and a better closeup.

    Do you see my amp? Look at the speaker cable plug ins. They are very finicky. There are times when the banana plugs don't make contact. ON AN ENTIRE CHANNEL.

    Are you putting this together? Do you see where I am leading you, where I am learning and following the same clues?

    The problem was never my crossover and new caps and bad soldering (though, yes, new and better soldering and more experience is now way better than first soldering). It was the connection between the banana plug and the amp all along!!!!!!!!!!!!!

    Yup. I'm an idiot. My DIY Parts Express amp is to blame.

    I plugged everything back up, set it up, played around with the amp's wires, and then bliss. The new caps, resistor, wires, terminals, strips--everything--it all worked, and it was amazing.

    I laid down on the ground for almost four hours. Metal, jazz, classical, folk, it all blew me away. And the longer I listened, the better it sounded. Even with just 50w at 6 ohm with a $30 DIY amp! I left it this way, cabinets unfinished for two weeks. I took photos. I loved the mid-century modern look. I loved the sound--they sounded way better, and even looked way better than my AMT Monitors.

    I became obsessed with perfection. I wanted every corner sharpened. I wanted the veneer to sing as high as the AMTs. I bought wood filler, various grades of sand paper, and new walnut lacquer and poly finish.

    I fell in love.
     
  8. 13stoploss

    13stoploss Active Member

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    So, hmm. You only get 60 minutes per comment to edit. Which means I missed the cutoff for #3 and #4. And, I don't know how to edit or delete those...
     
  9. Oozure

    Oozure Karma Bum

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    Become a subscriber and you will have unlimited time to edit. :thumbsup:
     
  10. 13stoploss

    13stoploss Active Member

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    I finally buttoned everything up. New boards, new wires, new caps, fixed the stupid banana plugs to my cheap PE DIY amp, and without hesitation, the ESS AMT-1a sprang to life. Maybe sprang is the wrong verb. It wasn't blooming. It wasn't dramatic. It was just a slow bubbling creek, continuously flowing. It was so natural and forward and normal, and exceptional!, I again laid down and just stayed there, listening, enjoying, reveling.

    [​IMG]

    The first thing I listened to was a CD of Nine Inch Nails' Ghosts disc, I-III. The first two tracks have a low freq piano that none of my speakers in my home theater or car or prevous 2-channel setup has ever been able to not distort. I cried. I heard clarity and balance. And then I played NIN The Fragile.

    I've long said to friends that I prefer horns for jazz and brass. But I put in some Miles Bitches Brew and, Geezus, was I imagining the detail and imaging? Was it as good as my Klipsch?

    Anyway, I still needed to finish the cabinets. Every corner has/d to be perfect.

    1.

    2.

    3. Second coat.

    4. Second coat sanded.

    5. And here's the learning curve heartbreak: I should've just gone new veneer from the start. The sand'able, paintable wood filler doesn't sand or paint or lacquer well.

    6. The walnut stain looks incredible, but it doesn't stain over the stain'able wood filler. :(

    So, here's where I was:

    [​IMG]

    Where am I currently? Not gotdamn perfect enough.

    Still going. Sill perfecting.

    New plan: sell the AMT Monitors, yet again rebuild the AMT-1a crossovers for bi-amplification. Except, I'm not sure how to do that. Anyone lend a hand?

    Follow my progress on Instagram.
     
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  11. 13stoploss

    13stoploss Active Member

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    How do I do that? How does that differ from my current status?
     
  12. Oozure

    Oozure Karma Bum

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    I believe if you go into your profile it will be under account upgrades. $25.00 per year. You will get access to several extra forums. Barter Town is one were you can buy or sell with other subscribers!
    Here is a link to a thread with more info: http://www.audiokarma.org/forums/in...s-it-and-how-do-you-become-one.124857/page-28 I skipped to more recent posts that may be more applicable since the software change.
     
  13. Porkloin

    Porkloin Oscar Heil Groupie Subscriber

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    Safe biamplification would be to switch out only the low-pass components of the crossover. In your case, you'd separate the woofer and tweeter legs of the crossover and bypass the cap and coil in the woofer leg. I belive that this part of it could be accomplished with a DPDT switch. Separating the woofer and tweeter legs could be accomplished with one of those biamp terminal plates, but that wouldn't quite fit in with your existing terminal scenario. Another SPDT switch could be employed, but you still need to install another set of terminals somewhere.
    Nice work on the crossover, by the way. I'll never understand why everyone doesn't neaten up those ugly old 70's crossovers. I'd probably say the same for the finish work if you posted some close up photos (hint-hint).
     
    Last edited: Nov 23, 2015
  14. wweigle

    wweigle Active Member

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    Nice write up. Much appreciated!!!
     
  15. essNeff

    essNeff AK Subscriber Subscriber

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    It was agonizing, measuring twelve times..........but I got mine to fit.
    Nice work!
    Thanks for the Pics.
     

    Attached Files:

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  16. Porkloin

    Porkloin Oscar Heil Groupie Subscriber

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    Are those bypass caps or additional caps paralleled in to achieve a given value?
     
  17. MarZutra

    MarZutra Super Member

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    Very good job. Kudos to you.... Good job! Very nice
     
  18. 13stoploss

    13stoploss Active Member

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    Thanks! With the coming holiday, I may have some time to complete the cabinets and take some photos. I'll definitely update as soon as I'm able.

    I very much appreciate this, but I don't understand it. To be completely honest, I'm in way over my head. I don't have any understanding of the work I'm doing, I'm just literally replacing stuff and putting it back together in order. I don't even know which caps are which!

    Re: bi-amplification, I've been comparing these AMT-1a crossovers with my AMT Monitor crossovers. The Monitors have two barrier strips so that one can use the regular passive part of the crossover, or skip/defeat it and go straight to the external, active, electronic crossover. Instead of barrier strips, I'd like to do this with four new banana plug terminals. But since this involves creative work, I don't understand how to do that. I need something to copy. Hopefully, years from now, I'll be laughing about my ineptitude. :)

    Thank you!

    This is what I should have done, but I got a little carried away...

    I know this wasn't directed to me, but I don't understand these English language words. Got link to a good primer?

    Thank you!
     
  19. Porkloin

    Porkloin Oscar Heil Groupie Subscriber

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    You're hardly in over your head, judging by the quality of your project. It's just another discipline to be mastered. I'd probably take a more cautious approach to biamping than ESS did with the Monitor. Granted, having no passive components between the driver and the amplifier theoretically makes for better sound, I think the risks outweigh the benefit. As I don't have total faith in an amplifier, I'd rather have some protection in place.
    I think your Elite with a solid state amp for the lows and a tube amp for the highs is the perfect biamping scenario.
     
  20. 13stoploss

    13stoploss Active Member

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    The Elite is long, long gone. Several years ago gone. This weekend I'll post some better pics of the current setup, as well as cabinet progress, but the setup now exists as an Emotiva XSP-1 gen2 pre-amp and a cheap get-me-by DIY 50w*2 amp. The amp is plenty loud for my room, but it just doesn't have that low-freq oomph I'm looking for.

    Goal? Emotiva XPA-2 SS + Elekit TU-8300R 300B tube.

    Why? Because I tried the bi-amp (Marantz 2230 for hi-freq and an Adcom GFA-555 for the low freq) and it was way more amazeballs than listening via the passive crossover with just the Marantz, the Adcom through the Marantz, or the Dynaco ST-70 through the Marantz. All three of those are now gone, too. I only now have the Emotiva pre-amp and the DIY amp. The setup I'm trying to build will eventually include DAC and media player...

    Not sure what you mean by risk and protection...?
     

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